Strange noise

[Inspector_77]

Now that I have the CEL issue resolved I need to isolate an intermittent noise. It sounds like a heat shield rattling but only occurs when accelerating hard or between 47 to 53 mph (approximately). A visual inspection reveals that the timing belt dust cover is missing a lower retaining bolt and is cracked. I am going to replace the cover and bolt but wonder if the timing belt tensioner pulley could be making the noise? I am unable to duplicate the noise whilst parked and revving the motor.

Scott

[gorkyb]

Last sound I had like that in my other car drove me crazy. I could swear it was coming from the transmission area (I got really scared), yet it sounded like a heat shield (very distinctive noise of sheet metal rattling), one day I took a couple hours and crawled under the car, it was coming from a heat shield between the CAT and the under body, very hard to see. Moral of my experience, never trust your ears only, specially when inside the cabin of the car, sound travels in a very sneaky way. What's different on yours is that it makes the noise only when car actually moving, so maybe look in the drive-train? if you suspect is the t-belt cover, take it off and take a drive without it, that'll tell you if it's something else. I'm sure fixkick has a way to determine if the tbelt tensioner pulley is good or bad. I had doubts on mine and just changed it since I was doing tbelt and head gasket on mine anyway.

[fixkick]

me 3, my cat shield rattles too, even my sons rattles , and its all new. we had to put wedges in the tins to stop that.
the tension'er , but the fan is there in the way ,keeping any stethoscope probe away from the bearing.
finding noises is more art than craft.
luck and determination. but using wedges can find them too, besides the stethoscope.

some times the air tube top , the mounts are loose or bolts missing.
put a tiny wedge in the cover, (wood, sliver, or cut wedge) see if that changes it. the sound or stops it.
just finding what part of car is making the noise, can be very hard, especially moving fast. very hard.

[TRACKERHACKER]

I once had a loose fan shroud that only made noise when moving. My cat cover also rattles when it wants to.

[gorkyb]

Today I had to rip off the heat shield off my cat, same reason, bad noise

[fixkick]

noise is complex. the FSM chapter 0? IIRC # is noise and is lacking.
1: find what area makes that noise, its not hard, there are cheap tools to do that ,try a wired or wireless sonic- ear. they cost about $50, you can even have friend drive and you listen.
2: you can use a rubber hose to ear to find the source. (under dash) under hood? (header shield behind exh manifold tubes cracked?)
3: if in the engine bay, you can drop belts. or put pressure on all (levers) to all engine mounted devices, to see if this pressure, stops the rattle. (shim the cat shield?.)
4: Ujoints, feel them flex them look for red rust dust , wicking from joint seams. they must not have play in the STAR. to yoke at all.
5: some 3speed, 2wd the tail shaft bushing fails, yes, a crappy bushing sold for 99cents too. 3sp is no class act.

you can drop all drive belts, even the water pump, start engine and test for 1min, so it dont overheat from dead cold.
the stethoscope (HF for $5) you can listen too all accessory bearings, they purr , listen to them all , you will see who sounds wrong fast.
I can drive and listen to gear box out shaft bearings, or axles. with the electronic ear. even driving.

last , i dropped in a new motor. and it started and run perfect but the banging sound, was the same as the last motor with a bad #4 rod bearing, MY HAIR stood on end.
the exhaust flange device was cracked and i missed that. the collector was boucning against the header,
also next kick 16v had 2 broken main intake main air pipe mounts broken, not only did it bank but sucks air and wrecked the MAF readings.

use levers and shims to find offending parts suspect.
jam them in and see if noise abates or changes.

the tools are worth 1/2 hr , shop labor, so IMO , are free. (and at the end, you get to keep the tool. and could sell it, and make all this free) Amazon sells them.


one such tool is the Steelman, 97220

http://www.amazon.com/Products-97220-Eng...B00396FBRY


there are other models, for faster discoveries, 4 channels,?